Class: OggInfo

Inherits:
Object
  • Object
show all
Extended by:
Forwardable
Includes:
Ogg
Defined in:
lib/ogginfo.rb

Constant Summary collapse

VERSION = 
"0.7.2"

Constants included from Ogg

Ogg::CHECKSUM_TABLE

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Ogg

compute_checksum, detect_codec

Constructor Details

#initialize(filename, charset = nil) ⇒ OggInfo

create new instance of OggInfo use of charset is deprecated! please use utf-8 encoded strings and leave charset to nil")



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# File 'lib/ogginfo.rb', line 39

def initialize(filename, charset = nil)
  if charset
    warn("use of charset is deprecated! please use utf-8 encoded tags")
  end
  @filename = filename
  @length = nil
  @bitrate = nil
  File.open(@filename, 'rb') do |file|
    begin
   	info = read_headers(file)
      @samplerate = info[:samplerate]
      @nominal_bitrate = info[:nominal_bitrate]
      @channels = info[:channels]
      @tag = info[:tag]
      # filesize is used to calculate bitrate
      # but we don't want to include the headers
      @filesize = file.stat.size - file.pos
    rescue Ogg::StreamError => se
      raise(OggInfoError, se.message, se.backtrace)
    end
  end

  @original_tag = @tag.dup
end

Instance Attribute Details

#channels ⇒ Object (readonly)

Returns the value of attribute channels.



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# File 'lib/ogginfo.rb', line 32

def channels
  @channels
end

#nominal_bitrate ⇒ Object (readonly)

Returns the value of attribute nominal_bitrate.



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# File 'lib/ogginfo.rb', line 32

def nominal_bitrate
  @nominal_bitrate
end

#samplerate ⇒ Object (readonly)

Returns the value of attribute samplerate.



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# File 'lib/ogginfo.rb', line 32

def samplerate
  @samplerate
end

#tag ⇒ Object (readonly)

tag is a hash containing the vorbis tag like "Artist", "Title", and the like



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# File 'lib/ogginfo.rb', line 35

def tag
  @tag
end

Class Method Details

.open(*args) ⇒ Object

"block version" of ::new()



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# File 'lib/ogginfo.rb', line 133

def self.open(*args)
  m = self.new(*args)
  ret = nil
  if block_given?
    begin
      ret = yield(m)
    ensure
      m.close
    end
  else
    ret = m
  end
  ret
end

Instance Method Details

#bitrate ⇒ Object

Calculated bit rate, also lazily loaded since we depend on the length



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# File 'lib/ogginfo.rb', line 78

def bitrate
  @bitrate ||= (@filesize * 8).to_f / length()
end

#close ⇒ Object

commits any tags to file



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# File 'lib/ogginfo.rb', line 149

def close
  if tag != @original_tag
    Tempfile.open(["ruby-ogginfo", ".ogg"]) do |tempfile|
      tempfile.close
      tempfile = File.new(tempfile.path, "wb")
      File.open(@filename, "rb") do | input |
        replace_tags(input, tempfile, tag)
      end
      tempfile.close
      FileUtils.cp(tempfile.path, @filename)
    end
  end
end

#hastag? ⇒ Boolean

check the presence of a tag

Returns:

  • (Boolean) 


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# File 'lib/ogginfo.rb', line 164

def hastag?
  !tag.empty?
end

#length ⇒ Object

The length in seconds of the track since this requires reading the whole file we only get it if called



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# File 'lib/ogginfo.rb', line 67

def length
  unless @length
    File.open(@filename) do |file|
      @length = compute_length(file)
    end
  end
  return @length 
end

#picture ⇒ Object

get the picture as an array of [extension, file_content] or nil if not existent



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# File 'lib/ogginfo.rb', line 109

def picture
  extensions = {
    "image/jpeg" => ".jpg",
    "image/png" => ".png" 
  }

  if content = tag["metadata_block_picture"]
    _, #type, # picture type
    _, # mime_type size
    mime_type, 
    _, # description size
    _, # description, 
    _, # width
    _, # height
    _, # color depth
    _, # number of color used
    _, #file_content_size, 
    file_content = content.unpack("m*").first.unpack("NNa10Na10NNNNNa*")
    return [extensions[mime_type], file_content]
  end
  nil
end

#picture=(filepath) ⇒ Object

set a picture (.jpg or .png) on the ogg file



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# File 'lib/ogginfo.rb', line 83

def picture=(filepath)
  ext = File.extname(filepath)
  mime_type = {
    ".jpg" => "image/jpeg",
    ".png" => "image/png"
  }[ext]
  description = "folder#{ext}"
  raw_string = 
    [3,               # picture type
     mime_type.size,
     mime_type,
     description.size,
     description,
     0,               # width
     0,               # height
     0,               # color depth
     0,               # number of colors used
     File.size(filepath),
     File.binread(filepath)
    ].pack("NNa*Na*NNNNNa*")
     
  @tag["METADATA_BLOCK_PICTURE"] = [raw_string].pack("m*").strip
end

#to_s ⇒ Object 



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# File 'lib/ogginfo.rb', line 168

def to_s
  "channels #{channels} samplerate #{samplerate} bitrate #{nominal_bitrate} #{tag.inspect}"
end